Hi we have 2 Yimmings chinese Syntec CNC machines in our shop the issue we have is getting the RPM past 12000 we have HSD spindle everything is wired correctly according to HSD. So I have a Delta VFD-B the label says 0-400 HZ we had a tech look at it he said we are only getting 5volts coming from the controller and he says he can put something on there to make it 10volts and I will be able to get the speed faster so if anyone knows about this please reply I hate to ruin the machine.